"make test" fails in build directory, but succeeds after "make install"

I'm not sure why this is the case, but when I did "make; make test" in the build directory, two tests failed. Subsequently I installed with "make install" and did "make test" again, just to check, and lo and behold the tests succeeded.

System is a Jetson Nano, Ubuntu 18.04 (L4T).

Mostly FYI, ok to close this but I wanted to write it down to share in case someone else hit the same snag.